The present invention relates to an outboard ribbed wheel hub and, especially, to an outboard ribbed wheel hub for use with trucks weighing in a range of 16,001 to 80,000 lbs.
Wheel hubs connect the wheel of a vehicle to the axle and, therefore, are subjected to significant compressive stress in bearing the weight of the vehicle. Furthermore, wheel hubs comprise a significant portion of the overall weight of vehicles designed for commercial freight hauling and similar uses. Such commercial vehicles are subject to state and federal regulations that impose restrictions on the overall weight of the loaded vehicle. Thus, any reduction in the weight of the wheel hubs will directly increase the amount of freight that can be hauled by such vehicles. However, the weight of a wheel hub cannot easily be reduced, because the wheel hub must be strong enough to withstand the stress of supporting the vehicle.
Wheel hubs are generally funnel shaped, having a cylindrical main body with a radial flange at one end. The wheel is secured to the radial flange and the axle is received within an axial bore through the main body. The side of the radial flange connected to the wheel is referred to as the outboard side, while the side oriented toward the axle is referred to as the inboard side.
During vehicle use, the compressive force imposed by the weight of the vehicle exerts significant bending stress on the radial flange. To increase the resistance of the radial flange to bending stress, traditional wheel hub designs feature a plurality of ribs positioned along the inboard side of the radial flange. The inboard ribs do not directly support the radial flange against the compressive force imposed by the weight of the vehicle, but merely resist the resulting bending stress by operating like a cantilever beam to strengthen and stiffen the radial flange.
However, compression loads are more efficiently supported than bending loads. Thus, the cantilever arrangement of the inboard ribs is relatively inefficient at supporting the radial flange against compressive force. Consequently, the inboard ribs of traditional wheel hub designs are larger and heavier than necessary to resist the compressive force imposed on the radial flange. Furthermore, the presence of the inboard ribs creates drastic cross-sectional changes in the profile of the radial flange. These drastic cross-sectional changes produce stress concentrations that are susceptible to cracking.
In addition, the axle is subjected to forces that tend to twist the axle away from the axis of rotation within the axial bore. This twisting force can cause deformation of the axial bore within the main body of the wheel hub. The inboard ribbed design of traditional wheel hubs does not provide any support or resistance against deformation of the axial bore caused by twisting of the axle.
Thus, it would be desirable to provide a wheel hub having increased resistance to compressive forces at a reduced weight in comparison to traditional inboard wheel hub designs. In addition, it would be desirable to provide a wheel hub that provides support for the axial bore against twisting of the axle.
These needs and other needs are satisfied by the present invention which comprises a wheel hub with a cylindrical main body, a radial flange and a plurality of radial ribs. The main body has an outboard end and an inboard end, and the radial flange has an outboard side and an inboard side. The radial flange is connected to and encircles the main body, with the radial ribs extending between the outboard side of the radial flange and the outboard end of said main body. In addition, the profile of the inboard side of said radial flange is a smooth, continuous curve.